OUT-OF-PHASE POWER AMPLIFIER AND METHOD AND DEVICE FOR REALIZING OUTPUT MATCHING THEREFOR AND POWER AMPLIFIER BRANCH

Abstract

 An out-of-phase power amplifier and a method for realizing output matching therefor, comprising: calculating an offset angle of a combiner according to signal power back-off of a signal source, i.e., a signal peak-to-average ratio; determining, according to the calculated offset angle, a ratio of optimal impedance Zm1 corresponding to a peak output power of a power tube to optimal impedance Zm2 corresponding to a mean output power of the power tube, wherein the ratio is a standing-wave ratio; determining, according to the size of an isostatic standing-wave ratio circle, a maximum power point impedance Zopt of the power tube by means of a load pull mode; by taking the maximum power point impedance Zopt as a reference point, finding out a back-off high-efficiency point impedance Zbk_eff on the isostatic standing-wave ratio circle; and matching the maximum power point impedance Zopt and the back-off high-efficiency point impedance Zbk eff, as corresponding impedance values, respectively to two input ends of the combiner.

Description

[0001] This application claims priority to Chinese patent application No. 201810011482.9 filed on January 5, 2018, disclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] The present invention relates to, but not limited to, power amplifier technology, for example, to an outphasing power amplifier, a method and device for achieving output matching of the outphasing power amplifier, and a power amplifier branch.

BACKGROUND

[0003] Currently, with the increasingly fierce competition in the wireless communication market, the performance of base station products has become the main focus of competition in the industry. As an important constituent part of the base station, a power amplifier (PA) is directly related to the quality of a signal transmitted by the base station and the communication effect. However, in order to achieve higher data transmission rate within a limited bandwidth, modern wireless communication systems all use complex digital modulation techniques. The complex modulation techniques coupled with multicarrier configuration result in improvement of a signal peak-to-average ratio (PAR). The improvement of PAR not only increases the difficulty of a linear index, but also makes it difficult to achieve a goal of high efficiency. This poses a great challenge to a current power amplifier design, that is to say, the power amplifier is required to overcome an increased linearity and achieve high back-off efficiency simultaneously.

[0004] In order to ensure that a transmitter has both high efficiency and high linearity, a relevant transmitter structure needs to be improved, such that high-efficiency switching power amplifiers may be applied, and linearization technology is used to ensure the linearity of a system.

SUMMARY

[0005] The present application provides an outphasing power amplifier and a method and device for achieving output matching thereof and a power amplifier branch, which can reduce design complexity.

[0006] The present application provides an outphasing power amplifier including a signal component separator, two or more power amplifier branches and a combiner. Each power amplifier branch of the two or more power amplifier branches includes an input matching circuit, a power tube and an output matching circuit.

[0007] The signal component separator is configured to separate a signal source into two outphasing constant envelope signals and output the two outphasing constant envelope signals to two input matching circuits respectively.

[0008] The input matching circuit is configured to achieve matching between an output impedance of a signal source and an input impedance of the power tube.

[0009] The power tube is configured to amplify a received signal.

[0010] The output matching circuit is configured to match an optimal impedance corresponding to a peak output power of the power tube and an optimal impedance corresponding to an average output power of the power tube to two input terminals of the combiner, respectively.

[0011] The combiner is configured to combine output power of two power amplifiers into one signal and output the one signal.

[0012] The present application further provides a method for achieving output matching of a power amplifier, and the method includes steps described below.

[0013] A maximum power point impedance Zopt and a back-off high efficiency point impedance Zbk_eff are determined according to a signal peak-to-average ratio of a signal source of a power tube. Distribution of the determined maximum power point impedance Zopt and distribution of the determined back-off high efficiency point impedance Zbk_eff are matched to two input terminals of a combiner.

[0014] The present application further provides a computer-readable storage medium, which is configured to store computer-executable instructions for implementing any one of the methods for achieving output matching described above.

[0015] The present application further provides a device for achieving output matching of a power amplifier, including a determination module and a matching module.

[0016] The determination module is configured to determine a maximum power point impedance Zopt and a back-off high efficiency point impedance Zbk_eff according to a signal peak-to-average ratio of a signal source of a power tube.

[0017] The matching module is configured to match the determined maximum power point impedance Zopt and the determined back-off high efficiency point impedance Zbk_eff to two input terminals of a combiner.

[0018] The present application further provides a power amplifier branch including an input matching circuit, a power tube and an output matching circuit.

[0019] The input matching circuit is configured to achieve matching between an output impedance of a signal source and an input impedance of the power tube.

[0020] The power tube is configured to amplify a received signal.

[0021] The output matching circuit is configured to match an optimal impedance corresponding to peak output power of the power tube and an optimal impedance corresponding to average output power of the power tube to two input terminals of the combiner respectively.

[0022] The present application further provides an apparatus for achieving output matching including a processor and a memory. The memory stores computer-executable instructions that can be run on the processor, when executed by the processor, the computer-executable instructions implement the following operations: determining a maximum power point impedance Zopt and a back-off high efficiency point impedance Zbk_eff according to a signal peak-to-average ratio of a signal source of a power tube; and matching the determined maximum power point impedance Zopt and the back-off high efficiency point impedance Zbk_eff to two input terminals of a combiner, respectively.

BRIEF DESCRIPTION OF DRAWINGS

[0023] The drawings are used to provide a further understanding of the technical solution of present application and form a part of the specification. The drawings and embodiments of the present application are used to explain the technical solution of the present application and not to limit the technical solution of the present application.

FIG. 1 is a schematic diagram showing composition of an outphasing transmitter system in the related art;

FIG. 2 is a schematic diagram showing composition of a switching mode power amplifier outphasing power amplifier in the related art;

FIG. 3 is a schematic diagram showing composition of an outphasing power amplifier according to the present application;

FIG. 4 is a flowchart of a method for achieving output matching of an outphasing power amplifier according to the present application;

FIG. 5A is a schematic diagram illustrating a variation curve of susceptance B at an input port of a combiner with an outphasing angle when a compensation angle is 23° according to the present application;

FIG. 5B is a schematic diagram illustrating a variation curve of conductance G at an input port of a combined with an outphasing angle when a compensation angle is 23° according to the present application;

FIG. 6 is a schematic diagram of determining an impedance point of a power tube in a load pull mode according to the present application;

FIG. 7 is a schematic diagram of an embodiment in which an output matching circuit achieves matching according to the present application;

FIG. 8 is a schematic diagram showing composition of a multipath outphasing power amplifier according to the present application; and

FIG. 9 is a schematic diagram showing composition of an outphasing power amplifier of another embodiment according to the present application.

DETAILED DESCRIPTION

[0024] Embodiments of the present application will be described hereinafter in detail in conjunction with the drawings. It is to be noted that if not in collision, the embodiments and features therein in the present application may be combined with each other.

[0025] A new high-efficiency transmitter structure includes an outphasing technology, an envelope elimination and restoration (EER) technology, an envelope tracking (ET) technology, a load modulation technology, a pulse width modulation (PWM) technology and the like. The outphasing technology can make a high-efficiency switching mode power amplifier be applied without affecting linearity of a transmitter by separating signals. Therefore, the outphasing technology has become one of the research focuses of high-efficiency power amplifiers and linearization technologies.

[0026] In the related art, an outphasing system mostly adopts two paths or more paths power amplifiers, and the two paths outphasing amplifier has become a mainstream of current applications due to their relatively simple circuit design. FIG. 1 is a schematic diagram showing composition of an outphasing transmitter system in the related art. As shown in FIG. 1, the outphasing transmitter system mainly includes three parts of a signal component separator (SCS), a high-efficiency power amplifier (PA) and a power combiner. The SCS separates an amplitude modulation/phase modulation signal into two outphasing constant envelope signals. The two outphasing constant envelope signals are amplified by two high-efficiency outphasing amplifiers and then restored to an amplitude amplified amplitude modulation/phase modulation signal by the power combiner. Generally, the power combiner needs to use a Cherie non-isolated combiner, in this way, when an outphasing angle of the input signal changes, loads of the two outphasing amplifiers will pull each other, such that the loads of the power amplifiers reach a maximum power point and a maximum efficiency point respectively with the change of the outphasing angle to achieve a purpose of improving output power and efficiency

[0027] From the above-mentioned principle, it could be concluded that in order to achieve a high working efficiency of the system, a design of the outphasing power amplifier must be able to ensure that a power amplifier load can still maintain the high working efficiency when changing within a certain range. Therefore, a key step to improve the efficiency of the outphasing technology is to select a high-efficiency power amplifier whose efficiency is not sensitive to load changes. For example, class-E and class-F switching mode power amplifiers (SMPA) have been widely used in an outphasing system. FIG. 2 is a schematic diagram showing composition of a switching mode power amplifier outphasing power amplifier in the related art. As shown in FIG. 2, the SMPA outphasing power amplifier mainly includes an input matching circuit, a power tube, an power amplifier output and harmonic control circuit.

[0028] Although both the class-E SMPA and the class-F SMPA used in an outphasing system can obtain higher efficiency and a certain bandwidth, due to inherent characteristics of the switching mode power amplifiers, it is inevitable to deal with a harmonics amplitude of a second, third or even higher and phase of a fundamental wave, and this control of harmonics will increase corresponding circuits. Therefore, the outphasing system has disadvantages of complicated circuit design, large printed circuit board (PCB) occupation area, difficult debugging and the like. If is achieved by a class-E power amplifier quasi-load insensitive technology, a more in-depth understanding of power tube packaging parameters is further needed, and power tube manufacturers may not be willing to provide the parameters, thus further limiting the application of this technology.

[0029] FIG. 3 is a schematic diagram showing composition of an outphasing power amplifier according to the present application. As shown in FIG. 3, the outphasing power amplifier includes a signal component separator, two or more power amplifier branches and a combiner, where each power amplifier branch of the two or more power amplifier branches includes an input matching circuit, an power tube and an output matching circuit.

[0030] The signal component separator is configured to separate a signal source into two outphasing constant envelope signals and output the two outphasing constant envelope signals to two input matching circuits respectively.

[0031] The input matching circuit is configured to achieve matching between an output impedance of a signal source and an input impedance of the power tube.

[0032] The power tube is configured to amplify a received signal.

[0033] The output matching circuit is configured to match an optimal impedance corresponding to peak output power of the power tube and an optimal impedance corresponding to average output power of the power tube to two input terminals of the combiner, respectively.

[0034] The combiner is configured to combine output power of two power amplifiers into one signal and output the one signal.

[0035] In the outphasing power amplifier provided in the present application, since the impedance matched to the combiner satisfies an impedance value required for load modulation, the output power of the outphasing power amplifier is ensured to be maximum, and the high-efficiency operation of the power amplifier is achieved. In addition, since the outphasing power amplifier of the present application does not need to process a harmonic amplitude of a second, third or even higher and phase of a fundamental wave, a design complexity is reduced, for example, a circuit design complexity is simplified, a PCB occupied area is reduced, and a debugging difficulty is also reduced.

[0036] In an embodiment, the combiner may be a Chireix non-isolated combiner with two inputs terminals connected to two power tube output matching circuits respectively, and an output terminal of the Chireix non-isolated combiner is connected to a 50 ohm terminal load.

[0037] In an embodiment, the combiner may also be a low impedance Chireix non-isolated combiner.

[0038] In an embodiment, the each power amplifier branch includes at least one of a first harmonic tuning circuit and a second harmonic tuning circuit, where the first harmonic tuning circuit is connected between the output matching circuit and the power tube; and the second harmonic tuning circuit is connected between the output matching circuit and the combiner. The harmonic tuning circuit is used to further improve the power amplifier efficiency.

[0039] In an embodiment, the output matching circuit is configured as below.

[0040] A compensation angle of the combiner is calculated according to a signal output power back-off (OPBO) of a signal source, that is, a signal peak-to-average ratio.

[0041] A ratio of the optimal impedance Z_m1 corresponding to the peak output power of the power tube to the optimal impedance Z_m2 corresponding to the average output power of the power tube is determined according to the compensation angle obtained from calculation, where the ratio is a standing wave ratio.

[0042] A maximum power point impedance Zopt of the power tube is determined by using a load pull mode according to a size of an equal standing wave ratio circle obtained from the standing wave ratio. A back-off high efficiency point impedance Zbk_eff is searched on the equal standing wave ratio circle by using the maximum power point impedance Zopt as a reference point.

[0043] An impedance value corresponding to the maximum power point impedance Zopt and an impedance value corresponding to the back-off high efficiency point impedance Zbk_eff are matched to the two input terminals of the combiner, respectively.

[0044] In an embodiment, the compensation angle ϕ_comp of the combiner may be calculated according to formula (1):

[0045] In an embodiment, the step of determining the standing wave ratio includes steps described below. Since the Chireix non-isolated combiner may be implemented by a microstrip circuit through an appropriate impedance such as Z0 in formula (3) and an electrical length such as θ in formula (2), a circuit schematic diagram and circuit parameters are shown in FIG. 4. In FIG. 4:

[0046] In formula (2) and formula (3), the signal peak-to-average ratio is corresponded to a microstrip impedance electrical length of the Chireix non-isolated combiner through the compensation angle ϕ_comp, and generally Zin is 50 ohms (Ω), R_L is 25Ω, and the corresponding Chireix non-isolated combiner is 50Ω.

[0047] Admittance Y, conductance G and susceptance B of an input port of the Chireix non-isolated combiner may be obtained according to the following formula:

[0048] From formula (4) and formula (5), it could be seen that during an input outphasing angle ϕ changes, a load impedance faced by two PA branches of the Chireix non-isolated combiner is always changing, and loads of the two PA branches are the same at two points of the compensation angle ϕ_comp and a 45° mirror image about the compensation angle ϕ_comp, and are both real numbers. The impedance faced by the two PA branches is different at the rest of the time. Two impedance crossing points of the two PA branches are a crossing point m1 and a crossing point m2, and impedances of the crossing point m1 and the crossing point m2 are determined by the compensation angle ϕ_comp. Assuming that admittance Y1 of an input port 1 and admittance Y2 of an input port 2 obtained according to formula (4) and formula (5) are equal, a relationship between the impedances of the crossing point m1 and the crossing point m2 (that is, the impedance Z_m1 of the crossing point m1 and the impedance Z_m2 of the crossing point m2) can be obtained and is shown in formula (6):

[0049] In order to ensure the system efficiency, in the present application, the impedance Z_m1 of the crossing point m1 corresponds to the maximum power point impedance Zopt, and the impedance Z_m2 of the crossing point m2 corresponds to the power back-off point impedance Zbk_eff.

[0050] In the outphasing power amplifier of the present application, load impedances only at the two points of the two PA branches are equal. Therefore, the two points are taken as a boundary condition of a design in the present application, and only when both the crossing point m1 and the crossing point m2 are satisfied to be high efficiency at the same time, the outphasing power amplifier can be ensured to achieve the high efficiency. Formula (6) determines a standing wave ratio of a terminal load, and thereby also determines that a standing wave ratio corresponding to the maximum power point impedance Zopt and the power back-off point impedance Zbk_eff is also

[0051] The applicant of the present application considers that the PA needs to maintain a state of high efficiency throughout an impedance change process. In practical application, according to probability density function (PDF) distribution of the signal, PA can be guaranteed to have a high average efficiency only by ensuring a high instantaneous efficiency between the maximum power point and the back-off power point. Therefore, according to the size of the equal standing wave ratio circle of formula (6), the maximum power point impedance Zopt of the power tube is found in the load pull mode, and then the back-off high efficiency point impedance Zbk_eff is searched, that is, found on the equal standing wave ratio circle by using the maximum power point impedance Zopt as the reference point. Then the maximum power point impedance Zopt and the back-off high efficiency point impedance Zbk_eff are matched as corresponding impedance values to the crossing point m1 and the crossing point m2, respectively, as corresponding impedance values. At this time, a transfer function H(s) of the output matching circuit should satisfy requirements of formula (7) and formula (8) simultaneously.

[0052] In formula (7) and formula (8), Zopt(s) and Zbk_eff(s) represent characteristic functions of Zopt and Zbk_eff, where the characteristic functions vary with frequency, respectively. In practical application, H(s) may be implemented by a microstrip circuit, and generally Z_m1 is a system impedance such as 50Ω.

[0053] The present application further provides a computer-readable storage medium, which is configured to store computer-executable instructions for implementing the method for achieving output matching described in any one of the embodiments.

[0054] The present application further provides a device for achieving output matching of a power amplifier, and the device includes a determination module and a matching module.

[0055] The determination module is configured to determine a maximum power point impedance Zopt and a back-off high efficiency point impedance Zbk_eff according to a signal peak-to-average ratio of a signal source of a power tube.

[0056] The matching module is configured to match the determined maximum power point impedance Zopt and the determined back-off high efficiency point impedance Zbk_eff to two input terminals of a combiner.

[0057] In an embodiment, the determination module is configured to: determine a compensation angle of the combiner according to the signal peak-to-average ratio of the signal source from the power tube; determine a ratio of an optimal impedance Zm1 corresponding to peak output power of the power tube to an optimal impedance Zm2 corresponding to average output power of the power tube according to the compensation angle, where the ratio is a standing wave ratio; determine the maximum power point impedance Zopt of the power tube, by using a load pull mode, according to a size of an equal standing wave ratio circle obtained from the standing wave ratio; and search the back-off high efficiency point impedance Zbk_eff on the equal standing wave ratio circle by using the maximum power point impedance Zopt as a reference point.

[0058] The present application further provides a power amplifier branch including an input matching circuit, a power tube and an output matching circuit.

[0059] The input matching circuit is configured to achieve matching between an output impedance of a signal source and an input impedance of the power tube.

[0060] The power tube is configured to amplify a received signal.

[0061] The output matching circuit is configured to match an optimal impedance corresponding to peak output power of the power tube and an optimal impedance corresponding to average output power of the power tube to two input terminals of the combiner respectively.

[0062] In an embodiment, the output matching circuit is configured as below.

[0063] A compensation angle of the combiner is determined according to a signal peak-to-average ratio of a signal source from the power tube.

[0064] A ratio of the optimal impedance Zm1 corresponding to the peak output power of the power tube to the optimal impedance Zm2 corresponding to the average output power of the power tube is determined according to the determined compensation angle, where the ratio is a standing wave ratio.

[0065] A maximum power point impedance Zopt of the power tube is determined by using a load pull mode according to a size of an equal standing wave ratio circle obtained from the standing wave ratio. A back-off high efficiency point impedance Zbk_eff is found on the equal standing wave ratio circle by using the maximum power point impedance Zopt as a reference point.

[0066] An impedance value corresponding to the maximum power point impedance Zopt and an impedance value corresponding to the back-off high efficiency point impedance Zbk_eff are matched to the two input terminals of the combiner respectively.

[0067] The present application further provides an apparatus for achieving output matching including a processor and a memory. The memory stores computer-executable instructions that can be run on the processor, when executed by the processor, the computer-executable instructions implement the following operations: determining a maximum power point impedance Zopt and a back-off high efficiency point impedance Zbk_eff according to a signal peak-to-average ratio of a signal source of a power tube; and matching the determined maximum power point impedance Zopt and the back-off high efficiency point impedance Zbk_eff to two input terminals of a combiner respectively.

[0068] The present application further provides a flowchart of a method for achieving output matching of an outphasing power amplifier, and the flowchart includes steps 1 to 4.

[0069] In step 1, a compensation angle of a combiner is calculated according to a signal output power back-off (OPBO) of a signal source, that is, a signal peak-to-average ratio.

[0070] Implementation of this step may refer to formula (1).

[0071] In step 2, a ratio of an optimal impedance Z_m1 corresponding to peak output power of a power tube to an optimal impedance Z_m2 corresponding to average output power of the power tube is determined according to the compensation angle obtained from calculation, where the ratio is a standing wave ratio.

[0072] The standing wave ratio in this step may refer to formula (6).

[0073] In order to ensure the system efficiency, in the present application, an impedance Z_m1 of a crossing point m1 corresponds to a maximum power point impedance Zopt, and an impedance Z_m2 of a crossing point m2 corresponds to a power back-off point impedance Zbk_eff.

[0074] In the outphasing power amplifier of the present application, load impedances only at two points of two PA branches are equal. Therefore, the two points are taken as a boundary condition of a design in the present application, only when both the crossing point m1 and the crossing point m2 are satisfied to be high efficiency at the same time, the outphasing power amplifier can be ensured to achieve high efficiency. Formula (6) determines a standing wave ratio of a terminal load, and thereby also determines that the standing wave ratio corresponding to the maximum power point impedance Zopt and the power back-off point impedance Zbk_eff is also

[0075] The crossing point m1 and the crossing point m2 are two impedance crossing points of the two PA branches of the outphasing power amplifier of the present application shown in FIG. 3, and impedances of the crossing point m1 and the crossing point m2 are determined by the compensation angle ϕ_comp.

[0076] In step 3, the maximum power point impedance Zopt of the power tube is determined by using a load pull mode according to a size of an equal standing wave ratio circle. A back-off high efficiency point impedance Zbk_eff is found on the equal standing wave ratio circle by using the maximum power point impedance Zopt as a reference point.

[0077] The applicant of the present application considers that the PA needs to maintain a state of high efficiency throughout an impedance change process. In practical application, according to probability density function (PDF) distribution of the signal, PA can be guaranteed to have a high average efficiency only by ensuring a high instantaneous efficiency between the maximum power point and the back-off power point. Therefore, according to the size of the equal standing wave ratio circle of formula (6), the maximum power point impedance Zopt of the power tube is found in the load pull mode, and then the back-off high efficiency point impedance Zbk_eff is found on the equal standing wave ratio circle by using the maximum power point impedance Zopt as the reference point. Then the maximum power point impedance Zopt and the back-off high efficiency point impedance Zbk_eff are matched as corresponding impedance values to the crossing point m1 and the crossing point m2, respectively, as corresponding impedance values. At this time, a transfer function H(s) of the output matching circuit should satisfy requirements of formula (7) and formula (8) simultaneously.

[0078] In step 4, the maximum power point impedance Zopt and the back-off high efficiency point impedance Zbk_eff are matched to the two input terminals of the combiner respectively as corresponding impedance values.

[0079] In the method for achieving output matching of the outphasing power amplifier provided in the present application, since the impedance matched to the combiner satisfies an impedance value required for load modulation, output power of the outphasing power amplifier is ensured to be maximum, and the high-efficiency operation of the power amplifier is achieved. In addition, since the outphasing power amplifier of the present application does not need to process a harmonic amplitude of a second, third or even higher and phase of a fundamental wave, a design complexity is reduced, for example, a circuit design complexity is simplified, a PCB occupied area is reduced, and a debugging difficulty is also reduced.

[0080] The technical solution of the present application will be described in detail below in conjunction with the application embodiments.

[0081] A signal source of about 7dB in a long term evolution (LTE) system is described as an example, and a compensation angle corresponding to a peak-to-average ratio of a signal source is about 23°. As shown in FIG. 5A and FIG. 5B, corresponding conductance G and susceptance B may be obtained from the above-mentioned formula.

[0082] In this embodiment, when the compensation angle is selected as 23°, corresponding load impedance susceptances are compensated to 0 at 23° and 67° respectively, that is, loads of the PA with the compensation angle of 23° and 67° are in a pure real resistance state, and a standing wave ratio relation between a crossing point M4 and a crossing point M7 is 5.66 and may be obtained from using formula (6). As shown in FIG. 5A and FIG. 5B, during the outphasing angle changing from 0° to 90°, output power indicated by arrows in FIG. 5A and FIG. 5B changes from large to small, and the load impedance of the PA tends to gradually increase. The PA in this embodiment maintains a state of high efficiency throughout an entire impedance change process. However, in view of the practical application, according to PDF distribution of the signal, PA can be guaranteed to have a high average efficiency only by ensuring a high instantaneous efficiency between the maximum power point and the back-off power point. Therefore, according to the size of the equal standing wave ratio circle of formula (6), as shown in FIG. 6, the maximum power point impedance Zopt of the power tube is found in the load pull mode, and the back-off high efficiency point impedance Zbk_eff is found on the equal standing wave ratio circle by using the maximum power point impedance Zopt as the reference point. Finally, the output matching circuit in FIG. 3 matches the maximum power point impedance Zopt and the back-off high efficiency point impedance Zbk_eff to the crossing point M4 and the crossing point M7 in FIG. 5B, respectively, as corresponding impedance values.

[0083] FIG. 7 is a schematic diagram of an embodiment in which an output matching circuit achieves matching according to the present application. As shown in FIG. 7, a power tube with a model of CREE CGH40045 is described as an example, assuming that a signal peak-to-average ratio is 7dB, and it could be obtained from the above analysis that theoretically the standing wave ratio corresponding to the maximum power point impedance and the back-off high efficiency point impedance of the power tube is 5.66. However, in view of non-ideality of a component in actual implementation, a value of the standing wave ratio may be appropriately increased, such as by about 10% in order to ensure an impedance variation range. In this way, an actual impedance conversion ratio, that is, the standing wave ratio is 6.3.

[0084] For convenience of measurement, assuming that a terminating load impedance ZL corresponding to the maximum power point is 50Ω in this embodiment, then a load impedance ZL' corresponding to the back-off high efficiency point is 315Ω according to formula (6). 50Ω is matched to the maximum power point of the power tube and 315Ω is matched to the back-off high efficiency point, and a relevant impedance relationship is shown in Table 1.

Table 1

Frequenc y (MHz)	ZL=50Ω		ZL'=315Ω
	Terminating load impedance corresponding to a maximum power point		Load impedance corresponding to a back-off high efficiency point
2140	3.969-j0.142	Maximum	1.255+j3.710	Back-off power
		power point impedance Zopt		point impedance Zbk_eff
	Output power (Pout) (dBm)	47.9	Pout (dBm)	41
	Efficiency (Eff) (%)	80.9	Eff (%)	86.9

[0085] Next, as shown in FIG. 6, first, according to a power contour line and an efficiency contour line, an impedance point that satisfies target saturation power and has relatively high efficiency is selected as the maximum power point impedance Zopt; then, by using the maximum power point impedance Zopt as the reference point, a point with back-off power reaching a target 7dB and having higher efficiency is found on a circle with the standing wave ratio of 6.3 and taken as the back-off high efficiency point impedance Zbk_eff; and finally, the maximum power point impedance Zopt and the back-off high efficiency point impedance Zbk_eff are matched to 50Ω and 315Ω respectively by using an advance design system (ADS) and other related circuit simulation tools through the output matching circuit.

[0086] As can be seen from the method for achieving the output matching network provided in the present application, when the power amplifier load changes in a standing wave ratio range of 1: 6.3, the power amplifier still maintains a relatively high efficiency.

[0087] In an embodiment, the combiner in the present application may also be a low impedance Chireix non-isolated combiner, such as a low impedance Chireix non-isolated combiner with a characteristic impedance of 7.93Ω. In this case, an impedance correspondence of the power impedance point output matching circuit is shown in Table 2.

Table 2

Frequency (MHz)	ZL=7.93Ω			ZL=50Ω
	Max power delivered			Back off power
2140	3.969-j0.142		Zopt	1.255+j3.710		Zbk_eff
	Pout (dBm)	47.9		Pout (dBm)	41
	Eff (%)	80.9		Eff (%)	86.9

[0088] In an embodiment, the present application may further be used in a multi-path outphasing system, and as shown in FIG. 8, FIG. 8 shows a composition architecture of a 4-path outphasing power amplifier.

[0089] In an embodiment, FIG. 9 is a schematic diagram showing composition of an outphasing power amplifier of another embodiment according to the present application. As shown in FIG. 9, in this embodiment, harmonic tuning circuits are added in the power impedance point matching network, that is, before and after the output matching circuit to further improve the power amplifier efficiency.

[0090] An embodiment of the present application further provides a computer-readable storage medium, which is configured to store computer-executable instructions for implementing the method for achieving output matching described in any one of the embodiments.

[0091] An embodiment of the present application further provides an apparatus for achieving media transmission, including a processor and a memory. The memory stores computer programs that can be run on the processor, and the computer programs are configured to: calculate a compensation angle of a combiner according to a signal OPBO of a signal source, that is, a signal peak-to-average ratio; determine a ratio of an optimal impedance Z_m1 corresponding to peak output power of a power tube to an optimal impedance Z_m2 corresponding to average output power of the power tube according to the determined compensation angle, where the ratio is a standing wave ratio; determine a maximum power point impedance Zopt of the power tube, by using a load pull mode, according to a size of an equal standing wave ratio circle; find a back-off high efficiency point impedance Zbk_eff on the equal standing wave ratio circle by using the maximum power point impedance Zopt as a reference point; and match the maximum power point impedance Zopt and the back-off high efficiency point impedance Zbk_eff to two input terminals of the combiner respectively as corresponding impedances.

Claims

1. An outphasing power amplifier, comprising: a signal component separator, two or more power amplifier branches and a combiner; wherein each power amplifier branch of the two or more power amplifier branches comprises an input matching circuit, an power tube and an output matching circuit; wherein
the signal component separator is configured to separate a signal source into two outphasing constant envelope signals and output the two outphasing constant envelope signals to two input matching circuits in the two or more power amplifier branches, respectively;
the input matching circuit is configured to achieve matching between an output impedance of the signal source and an input impedance of the power tube;
the power tube is configured to amplify a received signal;
the output matching circuit is configured to match an optimal impedance corresponding to a peak output power of the power tube and an optimal impedance corresponding to an average output power of the power tube to two input terminals of the combiner, respectively; and
the combiner is configured to combine output power of two power amplifiers into one signal and output the one signal.

2. The outphasing power amplifier of claim 1, wherein the each power amplifier branch comprises at least one of a first harmonic tuning circuit or a second harmonic tuning circuit; wherein
the first harmonic tuning circuit is connected between the output matching circuit and the power tube; and
the second harmonic tuning circuit is connected between the output matching circuit and the combiner.

3. The outphasing power amplifier of claim 1 or 2, wherein the combiner is a Chireix non-isolated combiner; or the combiner is a low impedance Chireix non-isolated combiner.

4. The outphasing power amplifier of claim 1 or 2, wherein the output matching circuit is configured to:

determine a compensation angle of the combiner according to a signal peak-to-average ratio of a signal source from the power tube;

determine a ratio of an optimal impedance Zm1 corresponding to the peak output power of the power tube to an optimal impedance Zm2 corresponding to the average output power of the power tube according to the determined compensation angle, wherein the ratio is a standing wave ratio;

determine a maximum power point impedance Zopt of the power tube, by using a load pull mode, according to a size of an equal standing wave ratio circle obtained from the standing wave ratio;

and search a back-off high efficiency point impedance Zbk_eff on the equal standing wave ratio circle by using the maximum power point impedance Zopt as a reference point; and

match an impedance value corresponding to the maximum power point impedance Zopt and an impedance value corresponding to the back-off high efficiency point impedance Zbk_eff to the two input terminals of the combiner, respectively.

5. A method for achieving output matching of a power amplifier, comprising:

determining a maximum power point impedance Zopt and a back-off high efficiency point impedance Zbk_eff according to a signal peak-to-average ratio of a signal source of a power tube; and

matching distribution of the determined maximum power point impedance Zopt and distribution of the determined back-off high efficiency point impedance Zbk_eff to two input terminals of a combiner.

6. The method of claim 5, wherein the determining the maximum power point impedance Zopt and the back-off high efficiency point impedance Zbk_eff according to the signal peak-to-average ratio of the signal source of the power tube comprises:

determining a compensation angle of the combiner according to the signal peak-to-average ratio of the signal source from the power tube;

determining a ratio of an optimal impedance Zm1 corresponding to peak output power of the power tube to an optimal impedance Zm2 corresponding to average output power of the power tube according to the compensation angle, wherein the ratio is a standing wave ratio; and

determining the maximum power point impedance Zopt of the power tube, by using a load pull mode, according to a size of an equal standing wave ratio circle obtained from the standing wave ratio; and searching the back-off high efficiency point impedance Zbk_eff on the equal standing wave ratio circle by using the maximum power point impedance Zopt as a reference point.

7. A computer-readable storage medium, which is configured to store computer-executable instructions for implementing the method for achieving output matching of any one of claims 5 to 6.

8. A device for achieving output matching of a power amplifier, comprising: a determination module and a matching module; wherein
the determination module is configured to determine a maximum power point impedance Zopt and a back-off high efficiency point impedance Zbk_eff according to a signal peak-to-average ratio of a signal source of a power tube; and
the matching module is configured to match the determined maximum power point impedance Zopt and the determined back-off high efficiency point impedance Zbk_eff to two input terminals of a combiner.

9. The device of claim 8, wherein the determination module is configured to:

determine a compensation angle of the combiner according to the signal peak-to-average ratio of the signal source from the power tube;

determine a ratio of an optimal impedance Zm1 corresponding to peak output power of the power tube to an optimal impedance Zm2 corresponding to average output power of the power tube according to the compensation angle, wherein the ratio is a standing wave ratio; and

determine the maximum power point impedance Zopt of the power tube, by using a load pull mode, according to a size of an equal standing wave ratio circle obtained from the standing wave ratio; and search the back-off high efficiency point impedance Zbk_eff on the equal standing wave ratio circle by using the maximum power point impedance Zopt as a reference point.

10. A power amplifier branch, comprising: an input matching circuit, a power tube and an output matching circuit; wherein
the input matching circuit is configured to achieve matching between an output impedance of a signal source and an input impedance of the power tube;
the power tube is configured to amplify a received signal; and
the output matching circuit is configured to match an optimal impedance corresponding to peak output power of the power tube and an optimal impedance corresponding to average output power of the power tube to two input terminals of the combiner, respectively.

11. The power amplifier branch of claim 10, wherein the output matching circuit is configured to:

determine a compensation angle of a combiner according to a signal peak-to-average ratio of a signal source from the power tube;

determine a ratio between of an optimal impedance Zm1 corresponding to the peak output power of the power tube to an optimal impedance Zm2 corresponding to the average output power of the power tube according to the compensation angle, wherein the ratio is a standing wave ratio;

determine a maximum power point impedance Zopt of the power tube, by using a load pull mode, according to a size of an equal standing wave ratio circle obtained from the standing wave ratio;

and search a back-off high efficiency point impedance Zbk_eff on the equal standing wave ratio circle by using the maximum power point impedance Zopt as a reference point; and

match an impedance value corresponding to the maximum power point impedance Zopt and an impedance value corresponding to the back-off high efficiency point impedance Zbk_eff to the two input terminals of the combiner, respectively.

12. An apparatus for achieving output matching, comprising: a processor and a memory; wherein the memory stores computer-executable instructions that can be run on the processor, when executed by the processor, the computer-executable instructions implement the following operations: determining a maximum power point impedance Zopt and a back-off high efficiency point impedance Zbk_eff according to a signal peak-to-average ratio of a signal source of a power tube; and matching the determined maximum power point impedance Zopt and the back-off high efficiency point impedance Zbk_eff to two input terminals of a combiner, respectively.

Drawing